Light-emitting apparatuses have been used for phototherapeutic and prevention apparatuses that prevent disease or reduce symptoms of disease by photoradiation, and for stroboscopic devices that emit light to a photographic subject.
A conventional light-emitting apparatus includes a discharge tube as a light source, and a light emission control circuit for controlling light emission from the discharge tube. The discharge tube includes a tubular glass bulb in which noble gas is enclosed, and a pair of electrodes attached to both ends of the glass bulb. The discharge tube and the light emission control circuit are connected via a lead wire, and contacts of the lead wires at the side of the discharge tube are connected to a pair of electrodes of the discharge tube. In general, this pair of electrodes and the lead wires are connected by soldering (e.g., PTL1 to PTL3). Accordingly, electrical connection is ensured by soldering the pair of electrodes and the lead wires. In addition, a structure to increase contact of the electrodes and lead wires by covering a connected part of the pair of electrodes and the lead wire with a heat-shrink tube is disclosed (e.g., paragraph 0060 and FIG. 7 of PTL3).
However, in repetitive emission or continuous emission from the discharge tube of the light-emitting apparatus, heat is generated by light emission. Generated heat accumulates at solder of the connected parts of the electrodes of the discharge tube and the lead wires, and thus the solder becomes hot. If the discharged tube is continuously used in the above condition, solder of the connected part stays hot, and solder becomes easily dissolved. As a result, the bonding strength of solder connecting the electrodes and lead wire reduces.